Synaptic reconstruction was a psychiatritric treatment used on planet Tilonus IV. During the procedure, the surgeons would neutralize the synaptic pathways in the cerebral cortex of a patient which were responsible for mental instability. This procedure was irreversible and altered the personality of the patient, creating a new person in the process.
In the delusion created by the neurosomatic technique, William T. Riker was a patient in the Tilonus Institute for Mental Disorders. He was looking for help with his hallucinations. Doctor Syrus wanted a settling of Riker's case quickly, so he offered two choices. The first option was reflection therapy. In this procedure, the patient interacted with the various facets of their personality. The facets were created holographically from scans made from the regions of a patient's brain which controlled emotions and memories. If successful, Riker would be fit to stand trial for a murder he may have committed. Option two was synaptic reconstruction. Riker opted for option one, whereby he was informed by Syrus he would begin the therapy in the afternoon. Some time later, Riker did not respond to the reflection therapy, because his delusions were becoming more elaborate. The hospital administrator Suna, seeing no other choice, came to the decision that Riker would undergo synaptic reconstruction. (TNG: "Frame of Mind")